John D’Annunzio
August 20, 2013
Once the moisture source is
eliminated insulation will physically dry out from normal building
environmental elements – building heat rises through insulation. It may appear
to be dry by sight – and in the case of some insulation materials – it may
appear to be dry from the touch. Once wet no insulation material fully recovers
its original structural and thermal capacity. Bottom line; just because it
looks dry does not mean it is dry.
The only true way to determine if
insulation is dry is through gravimetric testing. Gravimetric testing
determines the percentage of moisture present in an insulation. Each insulation
material has its own coefficient of acceptable moisture percentage. This is the
point at which the insulations thermal and structural capacity diminish.
It should be pointed out the IBC
code indicates that all wet insulation must be removed from an existing system
for a roof recover application. The code also states that only one recover
application is acceptable on a low-slope roof system. Furthermore, some States
and local codes indicate that if over 25% of a roof area has wet insulation –
the entire area requires removal.
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